[Amps] HF2500 Power Supply Caps

[Jim Thomson]

Date: Sat, 05 Apr 2014 08:41:38 -0700
From: Bill Turner <dezrat1242 at wildblue.net>
To: amps at contesting.com
Subject: Re: [Amps] HF2500 Power Supply Caps

On 4/5/2014 8:06 AM, Carl wrote:
> but more C doesnt buy anything useful. 

REPLY:

More C can actually be harmful. In case of an arc, more C just dumps 
more energy into the arc with potentially more damage.

73, Bill W6WRT

##  With a 50 ohm glitch Resistor installed, the peak fault current remains the same, regardless
of C used.   However, the 50 ohm glitch + total C  will  form a RC  time constant, whose duration
will be  longer when more C is used.   With 2500 vdc  + a 50 ohm glitch Resistor used, peak fault
current is 50 Amps..... which will easily blow open a 1-2 Amp rated HV fuse...and under 2 msecs. 

##  The 50 ohm glitch resistor LIMITS the peak fault current.   The HV fuse, just prior, and in series with the
50 ohm glitch resistor, INTERRUPTS the peak fault current.   You can cro-bar the supply all day long if you want.
All that happens is the HV fuse blows open.  

##  use whatever size cap you want.    The 440-600 uf types work just fine.  The bigger the total C used, the better the
dynamic regulation  of the supply.   The ripple is also lower, and in proportion to  C used.   A 600 uf cap will have one third the
ripple of a 200 uf cap..and way better dynamic regulation on ssb and cw.   Your load line is not all over the map. 
Now this all works with the proviso that a 50 ohm glitch R  and HV fuse is used.   

## As far as regulation goes, you require a plate xfmr that doesnt sag to begin with....and big enough ga wire from HV supply
back to main 200A panel.  You also  require  large enough rated relays and contactors.   Any Z between main panel and plate xfmr
will create V drops..which is bad news with any high C filter.  

Jim   VE7RF